With the development of world economy, mobile communication evolves continuously from a 3rd generation to a 4th generation, and there is an increasing demand for a multi-mode, multi-band, and multi-system mobile terminal such as a global-mode mobile phone or data card. It poses a great challenge to design of an antenna how to implement omnidirectional operation covering an ultrawide band of 0.8 GHz-5.5 GHz with a single antenna as a front portion of a mobile phone in a compact space, so as to save space and cost of the mobile terminal and facilitate development of a miniaturized and ultrathin mobile terminal.
At present, technology for widening the bandwidth of an antenna is mainly limited to improvement on the form of an antenna such as a planar inverted-F antenna (PIFA), an inverted-F antenna (IFA), a monopole antenna and the like, such as short-circuit point addition in multiple branches, appending of a parasitic structure, addition of a slotted structure, extension of a current path, and the like; and it is also possible to implement multi-band characteristics through different combinations of slots with microstrip feeders. However, with increase in the number of modes of mobile communication, expansion of the bandwidth of a mobile terminal as well as development of data services, there exists a serious bottleneck of a narrow bandwidth coverage and an increased demand for space by the parasitic structure in an aforementioned way of improvement, which is thus difficult to be implemented on the miniaturized and ultrathin mobile terminal.